Crystal oscillator



FIG. 1 is a front elevational view of a crystal oscillator showing our new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left elevational view thereof; and,

FIG. 6 is a right elevational view thereof. 

The ornamental design for a crystal oscillator, as shown and described. 